In the wireless communications arena, an incumbent user is generally defined as any existing user of frequency spectrum. Cognitive radio is a paradigm for wireless communication in which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently and utilize spectrum on a secondary basis without interfering with the incumbent users of a frequency band. This alteration of parameters is based on the active monitoring of several factors in the external and internal radio environment, such as radio frequency spectrum usage, user behavior and network state.
With the advent of cognitive radio networks and opportunistic spectrum access, the problem of accurate detection and classification of primary licensed users has taken utmost importance. The IEEE 802.22 standard allows unlicensed secondary wireless devices to operate in the TV white space but requires that there be minimum or no interference to the primary incumbents. Thus, CR devices must also sense for the existence of 802.22 based devices within the spectrum.
Accordingly, there is need to facilitate the ability of CR devices to sense for the existence of incumbent devices and/or other CR devices so as to avoid interference.
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